Increased Systemic C-Reactive Protein Is Associated With Choroidal Thinning in Intermediate Age-Related Macular...

C-reactive protein (CRP) and decreased choroidal thickness (CT) are risk factors for progression to advanced age-related macular degeneration (AMD). We examined the association between systemic levels of CRP and CT in patients with intermediate AMD (iAMD).

Patients with iAMD in the Colorado AMD Registry were included. Baseline serum samples and multimodal imaging including spectral domain-optical coherence tomography (SD-OCT), fundus photography, and autofluorescence were obtained. Medical and social histories were surveyed. CT was obtained by manual segmentation of OCT images. High-sensitivity CRP levels were quantified in serum samples. Univariate and multivariable linear regression models accounting for the intrasubject correlation of two eyes were fit using log-transformed CT as the outcome.

The study included 213 eyes from 107 patients with a mean age of 76.8 years (SD, 6.8). Median CT was 200.5 µm (range, 86.5-447.0). Median CRP was 1.43 mg/L (range, 0.13-17.10). Higher CRP was associated with decreased CT in the univariate model (P = 0.01). Older age and presence of reticular pseudodrusen (RPD) were associated with decreased CT (P < 0.01), whereas gender, body mass index, and smoking were not associated with CT. Higher CRP remained significantly associated with decreased CT after adjustment for age and RPD (P = 0.01).

Increased CRP may damage the choroid, leading to choroidal thinning and increased risk of progression to advanced AMD. Alternatively, CRP may be a marker for inflammatory events that mediate ocular disease. The results of this study further strengthen the association between inflammation and AMD.

Increased CRP is associated with choroidal thinning, a clinical risk factor for AMD.